John j



(No Model.) I

J. J. HAHN.

STEAM BOILER.

No. 499,828. Patented June 20, 1893.

Illi- WITNESSES.

A 7TORNEYJ'.

UNITED STATES PATENT OFFICE.

JOHN J. HAHN, OF NEW YORK, N. Y.,AssIc.'NoR or ONE-HALF TO ADOLPH' SOHINKEL, on SAME PLACE.

STEAM-BOILER.

SPECIFICATION forming part of Letters Patent No. 499,828, dated June 20, 1893. Application filed November 5, 1892. Serial No. 451,034. (No model.)

To all whom it may concern:

Be it known that'I, JOHN J. HAHN, of New York city, New York, have invented an Improved Steam-Boiler, of which the following is a specification.

This invention relates to a steam boiler which is so constructed that a volume of hot air is forced under pressure into the water chamber above the surface of the water. This compressed hotair serves a double purpose, first, to aid in heating the water and secondly to hold the damp steam down and to thus increase the effect of the fire upon the water.

The invention is particularly applicable to locomotive boilers, because more poweris developed within the same size of boiler, but theinvention may be applied to boilers generally- In the accompanying drawings: Figure 1 is an elevation partly in section of a locomotive provided with my improved boiler. Fig. 2 is a detail side view of the coil b; Fig. 3 a side View partly in section of a double acting pump for forcing the hot air into the coil and Fig. 4 an elevation of cam f, with the axle f in section.

The letter a, represents a tubular or other boiler, within which there is contained a coil 1). This coil is placed within the upper part of the boiler and above the water level. The coil 1), is connected by a pipe 0, to a warm air supply such as the fire box 6, of a locomotive. The pipe 0, .is provided with a stop cock 0, and enters one of the cylinders d, of a pump, which is also connected by pipe 0 with the fire box 6. The piston 61', of the pump is driven bya cam or eccentricf, on the axlef, of the locomotive which engages a slide or cross head d of the piston. The construction of the cam is best shown in Fig. 4. It is composed of two sections keyed around the axle f, by countersunk bolts f while collars g, serve to hold the cam in place. The pump will draw hot air from the fire box through of the boiler is increased and fuel is economized. If the pressure in the boiler exceeds the pressure in the coil, the valveb', will be closed and the supply of hot air will be cut off, excepting a small quantity escaping through an opening b In Fig. 3 I have shown a double acting pump having two cylinders d, so that compressed hot air is forced into the coil or coils at eacli partial stroke of the piston.

What I claim is 1. The combination of a steam boiler with a coil placed within the upper part of the boiler shell above the water level and with a pump for forcing compressed hot airthrough the coil and into the boiler substantially as specified.

2. The combination of a steam boiler with an inclosed coil, a driving shaft, a cam mounted thereon, a pump operated by the cam and with a pipe that connects the pump with the 5 coil, substantially as specified.

3. The combination of a steam boiler having a fire box with an inclose'd coil, a valve controlling the discharge opening of the coil,

a driving shaft, a cam mounted thereon, and 80 with a pump operated by the cam and connected to the coil and to the fire box,substantially as specified.

JOHN J. HAHN. 

